1. Field of the Invention (Technical Field)
The present invention relates to measuring the hydraulic conductivity of layers of the Earth's subsurface, and particularly to an apparatus and method, deploying a flexible everting liner, for providing a continuous direct measurement of the location and flow rate of geological fractures and permeable beds intersecting a borehole.
2. Background Art
Many kinds of measurements may be made to assess the characteristics of fluid flow paths in the Earth's subsurface. Most measurements are made in a borehole drilled into the geologic formations of interest. The common borehole is measured with a variety of “logging” techniques to locate fractures, to measure flow velocities in the hole, to measure the temperature effects of flowing water, and to identify potential flow paths such as permeable beds with unique measurable properties. Known measurement techniques typically involve acoustics, electrical resistivity, video scans, natural radiation detection, and induced radiation. Many of these measurements using current techniques are only indirectly related to the specific flow characteristics desired. Other measurement approaches for flow path assessments involve the use of “packers”: single, double, or more, inflatable bladders which are used to isolate a portion of the hole. The isolated portion, comprising only a section of the vertical extent of the borehole, is then pumped to assess the flow from, or into, the hole wall under specific driving conditions.
It is desirable to have an improved mode for measuring hydraulic conductivity and related characteristics more directly. The present invention does so by deploying a special liner apparatus down the borehole. Everting liner technology is best described in patents previously issued to the inventor of the present application. These patents are U.S. Pat. No. 6,298,920 issued Oct. 9, 2001; U.S. Pat. No. 6,283,209 issued Sep. 4, 2001; U.S. Pat. No. 6,244,846 issued Jun. 12, 2001; and U.S. Pat. No. 6,026,900 issued Feb. 22, 2000. Beneficial reference may be made to these patents, and their teachings are hereby incorporated by reference.